THE ANCIENT FERNS 



Osmunda regalis, the only European member of it, has already been described in some 

 detail in Chapter 3. A single species, however, is insufficient basis for discussion of a 

 group, and in this one instance it seems desirable to break our general rule of avoidance 

 of botanic gardens in order to supplement it. This is perhaps less harmful here than it 



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Fig. 274. Meiosis in British Hymenophyllum, permanent acetocarmine. x 1000. 

 a. H. milaterale Bory. n= 18. b. H. tunbridgense (L.) Sm. n= 13. 



Fig. 275. Hymenophyllum tunbridgense (L.) Sm. Spiral structure of chromosomes 

 at anaphase of the first meiotic division, x 2000. 



might be elsewhere, because all members of the group are so distinctive and possess such 

 well-defined geographical ranges that confusion between them is virtually impossible, 

 even in the absence of all records of the actual sources of collections. 



The living Osmundaceae consist of the three genera, Osmunda, Todea and Leptopteris. 

 The first contains about ten mainly temperate species, collectively distributed over a 

 very large part of the earth's surface. The second, Todea, is monotypic, consisting only 

 of T. Barbara (L.) Moore (sometimes known as T. africana Willd.), a subtropical plant 



Fig. 276 (opposite). Osmunda palustris. Silhouette of living leaves from a horticultural source, a, sterile; 

 b, fertile. Natural size. 



